I am supposed to decorate a costco cake for Saturday party and I will be covering it with fondant. I just want to get an idea of how early I should order/start decorating.

Thanks!

*snark on* Since those things are frozen for ten months before you'll get it, you shouldn't need to worry about freshness.*snark off*

Seriously, even if you start on Wednesday and cover it in fondant there shouldn't be a "quality" problem.